The present invention relates generally to a cooling system for a turbomachine; more specifically, but not by way of limitation, to an integrated cooling system that requires less energy to operate.
Generally, many components and/or systems of a powerplant require cooling. FIGS. 1A and 1B, collectively FIG. 1, is a schematic illustrating known independent cooling systems for a turbomachine. FIG. 1 illustrates a turbomachine 100, a heat recovery steam generator (HRSG) 115, and a stack 120.
Generally, the turbomachine 100 may comprise multiple compartments, which enclose the components of the turbomachine 100. FIG. 1 illustrates two of the multiple compartments: a first compartment 105 and a second compartment 110. Although the present invention is described with repeated references to the first compartment 105 and the second compartment 110, the present invention is not limited to the first compartment 105 and second compartment 10. Furthermore, an embodiment of the present invention may be adapted to each of the multiple compartments, some of which may not be illustrated in the Figures.
The first compartment 105 may enclose a compressor section 125 which drawings in ambient air, illustrates by an arrow. The ambient air enters the compressor section 125, is compressed and then discharged to a combustion system 130, where a fuel, such as a natural gas, is burned to provide high-energy combustion gases; which drives a turbine section 140. In the turbine section 140, the energy of the combustion gases is converted into work, some of which is used to drive the compressor section 125, with the remainder available to drive a load such as, but not limiting of, a generator (not illustrated). While the turbomachine 100 operates, these components emit heat that raises the temperature of the environment enclosed by the first compartment 105.
The first compartment 105 may also include a first compartment (FC) cooling circuit 155, which serves to lower the temperature of the environment within the first compartment 105. An embodiment of the FC cooling circuit 155 may comprise a FC air circulation device 160, a FC supply line 165, and a FC discharge line 170. An embodiment of the FC air circulation device 160 may comprise at least one fan. The FC cooling circuit 155 may draw in air that derives from the ambient. For example, but not limiting of, the air may flow directly from the ambient; or the air may flow from a ducting system that conditions the air, which originates from the ambient.
Next, the FC cooling circuit 155 may move the ambient air through the FC supply line 165 into the first compartment 105. Here, the ambient air becomes heated, as some of the heat from the first compartment 105 is removed. Then, the heated air is discharged to the atmosphere via the FC discharge line 170.
For example, but not limiting of, the FC cooling circuit 155 draws in ambient air, removes heat from the first compartment 105. This heated air may then be discharged to atmosphere at 200 degrees Fahrenheit or greater.
The second compartment 110 may enclose an exhaust frame 145, which generally serves to move the exhaust generated by the turbomachine 100 towards an HRSG 115. Here, the exhaust frame 145 channels the exhaust that flows from the turbine section 140 to the HRSG 115 via a shell. An embodiment of the shell comprises a double wall 150. The double wall 150 may comprise a circular annulus that surrounds the exhaust frame 145, as illustrated in FIG. 1B. An alternate embodiment of the shell may comprise a single shell, wherein the single wall may comprise cooling holes and/or a serpentine cooling path for cooling the exhaust frame 145.
The second compartment 110 may also include a second compartment (SC) cooling circuit 175, which serves to lower the temperature of the environment within the second compartment 110. An embodiment of the SC cooling circuit 175 may comprise a SC air circulation device 180, and a SC supply line 185. An embodiment of the SC air circulation device 180 may comprise at least one blower. The SC cooling circuit 175 may draw in ambient air, then move the ambient air through the SC supply line 185 into the double wall 150. Here, the ambient air serves to cool the exhaust frame 145, which is heated by the exhaust flowing therein. The ambient air becomes heated and is discharged to the HRSG 115 where the heated air mixes with the exhaust.
For example, but not limiting of, the SC cooling circuit 175 draws in ambient air which may become heated to 350 degrees Fahrenheit or greater. This heated air is then mixed with the exhaust that may be at a temperature of 1150 degrees Fahrenheit or greater.
There may be a few concerns with the current cooling systems. The FC air circulation device 160 and the SC air circulation device 180 typically require electricity to operate. The devices 160,180 may be considered parasitic loads on the turbomachine 100. Generally, parasitic loads consume a portion of the energy generate by the turbomachine leading to a reduction in the overall efficiency.
Also, temperature dilution occurs when relatively cooler air discharging from the double wall 150 mixes with the significantly hotter exhaust discharging from the internal portions of the exhaust frame 145. Temperature dilution may be considered an irreversible energy loss, which leads to less energy available for the bottoming cycle of the HRSG 115. This temperature dilution may cause an approximately 10 to 20 degree temperature suppression, leading to a decrease in the efficiency of the turbomachine 100 and the HRSG 115.
For the foregoing reasons, there is a need for an integrated turbomachine cooling system. The system should integrate the cooling of multiple turbomachine compartments. The system should also reduce the amount of parasitic loads on the turbomachine. The system should also decrease the effect of temperature dilution.